This invention relates generally to automatic belay apparatus and its use; and more particularly it concerns the provision of safe, easily used, simple and compact, fall protection/lowering apparatus which can be employed in many situations to save lives and also for recreational purposes.
There is a known phenomenon that when a rope is wrapped around a fixed cylinder an X tension is applied to one end of the rope, a reactive force less than X (we will call Y) will stop the rope from slipping. More wraps around the cylinder will reduce the required Y force necessary for equilibrium.
Once equilibrium is attained between X and Y, reducing Y force by some xcex94 amount will allow the rope to slip. The amount of reduction in Y is dependent upon, among other things, the elasticity of the rope, the number of wraps around the cylinder, the diameter of the cylinder, and the co-efficient of friction between the rope and the cylinder.
To belay in nautical terms, is to xe2x80x9cmake fast (a rope) by winding on a cleat or pinxe2x80x9d.
If one is climbing, to be belayed is to be protected (by a rope) from falling. This is accomplished by wrapping a rope around the belayer, or some other object, so as to reduce the Y tension when a climber falls, creating X tension. The governing equation depicting this phenomenon is:
Therefore, the greater number of wraps (radians), the lower Y is required for equilibrium.
And here is the paradox. If one wished Y to be minimal, multiple wraps are required; but, if one wishes to take up slack on the X rope when climbing by taking up Y tension, the weight of the rope X will be multiplied by the same factor (but in reverse) as when the climber falls which might make it impossible to take up slack, and hence a non-functional device.
As one example:
For a wire rope, with 5xc2xd wraps around a 3xe2x80x3 pipe (3.5 O.D.),
X=50# and Y=0.12#
Therefore, the amplification factor is             50      ⁢      #              .12      ⁢      #        =  400
Now, remove the 49# weight leaving a 1# rope and try to pull Y. Y=1#xc3x97400=400# to take up slack. This is not possible, or practicable.
Accordingly, there is need for improved apparatus to overcome the above problem so that slack can be automatically taken up while using the multiplying effect of multiple wraps; and there is need for apparatus which can be easily used for safe lowering of weights, as from great heights.
It is a major object of this invention to provide improved fall protection/lowering apparatus and methods, meeting the above needs. Basically, the apparatus of the invention is used for controlling vertical movement of a first weight (as for example a human being or other load), and comprises:
a) a first element rotatable in one direction about an axis and a structure blocking said first element against rotation in the opposite rotary direction,
b) a second element acting as a guide,
c) a control weight,
d) and lines supporting said first weight and control weight by said elements, and including a first line wrapping about the first element and a second line entraining the second element, whereby changes in force exertion on the control weight determine alternative existence of a first mode of operation wherein line slippage relative to the first element allows the first weight to descend, and a second mode of operation wherein line non-slippage relative to the first element thereby blocks descending of the first weight,
e) and wherein
i) the first line that wraps about the first element has line portions that extend downwardly to support loading imposed by the first weight and control weight, respectively,
ii) the second line that entrains the second element has one line portion that extends downwardly to support control loading imposed proximate but independently of the first weight, and the one line portion not connected to the first weight, and another line portion to support loading imposed by the control weight.
Typically, the first line that wraps about the first rotor has line portions that extend downwardly to support loading imposed by the first weight and control weight, respectively; and the second line that entrains the second element also has line portions that extend downwardly to support loading imposed by the first weight and control weight respectively.
Another object is to provide a first rotor element with an extended surface to engage multiple, non-interfering wraps of the first line.
A further object is to provide the first rotor with two axially spaced generally conical portions, and a generally cylindrical portion intermediate those conical portions. Typically, the conical portions may have wrap engaging angularities characterized as maintaining the first line wraps free of sidewise interengagement or interference during operation of the apparatus to lower the first weight.
Accordingly, optimum operability and functioning of the first line and first rotor are maintained.
Yet another object is to provide the first rotor element with an axial through passage, the second line passing through that passage, whereby a high degree of compactness of the equipment is achieved.
An additional object is to provide support structure for a human being who imposes the first weight in order to be lowered, such support structure defined by an upright strut connected to the line wrapped about the first rotor, and a seating ledge connected to the strut. That ledge may advantageously include at least one folding section having an up-folded position extending generally parallel to the upright stem, and a down-folded position extending generally laterally to seat the human being.
In use, the first rotor, i.e. a cylinder for example, is allowed to rotate freely in one direction (while taking up slack), and prevented from rotating in the opposite direction while resisting a fall. The taking up of slack is accomplished by hanging a weight on the Y reactive side of the cylinder greater than the weight of the rope on the X tension side of the cylinder; hence, in the above one example, Y need only be 1# to take up slack but it is strong enough to resist a 400# load during a fall.
If the device is to be used by a climber, once the climber has climbed he must be able to lower himself. This can be accomplished by attaching a separate control rope to the Y reactive weight, running this control rope through the first rotor element, or over a freely rotating sheave, and then attaching the control rope to the X load. By shortening the control rope, the Y reactive force will be reduced until slippage occurs. Since X and Y will remain the same distance apart during slippage, slippage will continue unabated until the control rope is allowed to lengthen, for example lifted.
It is another object of the invention to provide a governor that engages a line to slow the rate of descent of the first weight as that rate of descent increases. As will be seen, one advantageous and simple governor includes at least two sheaves about which the line is entrained, together with relatively rotatable discs in a fluid medium, certain discs driven by the rotor to produce fluid shear acting increasingly to slow rotation of the rotor in response to increasing rates of rotation of the rotor and said certain discs. Accordingly the rate of descent of the weight can be slowed by controlling the rate of ascent of the control weight, as that rate tends to increase.
Yet another object of the invention is to provide a hoist to hoist weight of a line that extends between a control weight and the first rotor, thereby to eliminate or substantially reduce the effect of decreasing line weight on control of the system, as the control weight ascends (which makes the first weight fall faster). In this regard, the hoist may advantageously be very simply and effectively integrated with the governor; for example, a line may be entrained by two governor sheaves A and B; and a control line may be entrained by two hoist sheaves C and D; a primary axle may carry the A and C sheaves to rotate together; and a secondary axle may carry the B and D sheaves to rotate together.
A further object includes provision of a guide line having an upper portion that suspends the rotor about which the defined first line is wrapped, and at an upper location, the guide line also having a lower portion that is anchored at a fixed lower location. That lower portion can be released to permit bodily lowering of the rotor, as will be seen, whereby a climber or person whose weight is suspended by the rotor, can be safely lowered in an emergency. In this regard, the path of descent or ascent of the control weight can be guided by the guide line, angled so as not to interfere with the paths of ascent or descent of the person whose weight is suspended by the rotor.
An additional object includes provision of a slack detector engaging a portion of the line, below the level of the rotor; together with a signal generator to generate a detectable signal upon occurrence of slack in said engaged portion of the line. The slack detector may advantageously have first and second parts that are relatively movable in the direction of the line, the parts having associated grips to grip the line at locations spaced apart therealong, the signal generator (electrical or mechanical or other) being responsive to relative movement of such parts.
A further object includes provision of fin structure on the first rotor to act as a heat radiator during rapid slippage of the line in frictional wrapping or unwrapping engagement with the rotor, acting to generate heat.
Another object is to provide circularly spaced, axially extending protrusions on the first rotor, to be frictionally engaged by the first line wraps, to establish better control of wrap engagement with the rotor.
A yet further object is to provide apparatus for use in climbing of a pole, by a climber, and which includes
a) a climber""s harness for supporting the torso of a climber climbing the pole,
b) first means for elevating that harness as the climber climbs the pole, and for blocking lowering of the harness,
c) and second means carried by the pole for enabling climbing pull-up relative to the pole.
As will be seen, the second means may include a series of holes in the pole and spaced apart lengthwise of the pole to receive insertion of manually graspable pegs successively inserted into vertically successive holes. Typically, two of such pegs may be located respectively at opposite sides of the pole.
The first means referred to may include
a) a first element including a rotor rotatable in one direction about an axis and blocked against rotation in the opposite rotary direction,
b) a second element acting as a guide,
c) a control weight,
d) lines for supporting the climbers weight and the control weight by said elements, and including a first line wrapping about the rotor and a second line entraining the second element, whereby changes in force exertion on the control weight determine alternative existence of a first mode of operation wherein line slippage relative to the rotor allows the first weight (climber""s weight) to descend, and a second mode of operation wherein line non-slippage relative to the rotor thereby blocks descending of the first weight.
Control means may be provided for supporting the rotor to be lowered relative to the pole, for safety purposes; and such control means may include a control line extending to a control location, to be extended for lowering the rotor relative to the pole.
These and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following specification and drawings, in which: